1. Field
Although not so limited in its utility or scope, implementations of the present invention relate generally to the fabrication of optical image transfer bundles (also known as “image-conducting bundles”) of the type comprising a multitude of elongated light-conducting fibers extending between light-collecting and light-emitting ends and, more specifically, to image-transfer bundles having, between the light-collecting and light-emitting ends, flexible and rigid regions.
2. Brief Description of Illustrative Environments and Related Art
Known to practitioners of the optical fiber arts is that, in an image-conducting optical fiber bundle (hereinafter also “image-conducting bundle” or, simply, “image bundle”), wherein a multitude of relatively long and thin fibers of light-conducting material is bundled together and used to transmit image-forming light from one location to another, it is important that each fiber of the image bundle be orderly and accurately positioned therein with at least the opposed input and output ends of the image bundle substantially geometrically identical in character. In certain types of fiberscopes or other such devices that comprise a relatively thin but long bundle of light conducting fibers, it is often desirable to fasten only the opposite ends of the individual fibers in fixed relation with each other and to allow the intermediate portions of the fibers to be free to flex individually. An image bundle constructed in this manner is flexible throughout a region between its input and output ends and is useful under circumstances in which image-forming light must be directed from one location to another along irregularly shaped paths as, for instance, in an endoscope.
In order to form an image bundle that is capable of accurately transferring an optical image from one location to another, the opposed entrance and exit ends of the individual light-conducting fibers must be grouped in accurately aligned parallel side-by-side nested relation with each other and identically geometrically patterned to cause each part of the light (e.g., “pixel”) of an optical image admitted in one location at the entrance end of each fiber of the group, to be emitted from the exit end of said group in a corresponding location so as to output an image similar to the input image. When the fabrication of flexible image bundles exhibiting acceptable image integrity and resolution was a nascent art, the accurate assembly of the input and output ends of image bundles was difficult, time consuming and costly. In the intervening decades, however, methods of manufacturing flexible image bundles have been simplified and, thus, rendered more accurate, less time-consuming and less expensive.
In accordance with one industry-wide method of fabricating a flexible image bundle, a continuous light-conducting fiber is helically wound onto a mandrel in order to form adjacent convolutions (i.e., windings) about the mandrel. Once a helix of predetermined width is formed, a predetermined “ends region” of the successive convolutions is laterally bonded such that the portions of the continuous fiber within that predetermined ends region are fixed in side-by-side relationship with each other prior to the removal of the helix from the mandrel. The bonding is conventionally achieved by application of a suitable glue, cement or epoxy. Once the bonding agent cures, the helix is removed from the mandrel.
In order to form two-dimensional input and output ends, a plurality of similarly fabricated helixes is assembled with the ends regions of multiple helixes stacked in aligned superimposed relationship and these ends regions are then secured in fixed relationship by a clamp, housing or a bonding agent such as cement, glue or epoxy. The assembly of ends regions is then cut transversely to the axes of the constituent fibers. A portion of the cut ends region on either side of the cut becomes one of (i) the input end and (ii) the output end of the image bundle. It will be readily appreciated that, by such a method, the positional correspondence of the entrance and exit ends of each fiber within, respectively, the input and output ends of the image bundle is assured.
As previously alluded to, image bundles formed in general accordance with the aforementioned method, or a method similar in result, are used in a wide variety of applications. In order to protect, and sometimes direct, the flexible portions of the constituent fibers of an image bundle, at least the intermediate flexible region is housed in a rigid, pipe-like housing or a flexible, sleeve-like housing. It is sometimes necessary when housing intermediate regions to clamp or bend them, but doing so may cause stress or damage to flexible regions of fibers within the bundle. Accordingly, there exists a need for a an image bundle that is at least partially flexible between rigidly fixed input and output ends, but that includes at least one rigid region intermediate the input and put ends, and methods of fabricating the same.